We consider multiple-input multiple-output (MIMO) radar systems withwidely-spaced antennas. Such antenna configuration facilitates capturing theinherent diversity gain due to independent signal dispersion by the targetscatterers. We consider a new MIMO radar framework for detecting a target thatlies in an unknown location. This is in contrast with conventional MIMO radarswhich break the space into small cells and aim at detecting the presence of atarget in a specified cell. We treat this problem through offering a novelcomposite hypothesis testing framework for target detection when (i) one ormore parameters of the target are unknown and we are interested in estimatingthem, and (ii) only a finite number of observations are available. The testoffered optimizes a metric which accounts for both detection and estimationaccuracies. In this paper as the parameter of interest we focus on the vectorof time-delays that the waveforms undergo from being emitted by the transmitantennas until being observed by the receive antennas. The analytical andempirical results establish that for the proposed joint target detection andtime-delay estimation framework, MIMO radars exhibit significant gains overphased-array radars for extended targets which consist of multiple independentscatterers. For point targets modeled as single scatterers, however, thedetection/estimation accuracies of MIMO and phased-array radars for thisspecific setup (joint target detection and time-delay estimation) arecomparable.
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